package com.codingxyz.simple.prodconsumer;


import java.util.concurrent.locks.Condition;
import java.util.concurrent.locks.Lock;
import java.util.concurrent.locks.ReentrantLock;

/**
 * 多线程用while判断，慎用if
 */
class ShareData{

    private int number = 0;

    private Lock lock = new ReentrantLock();
    private Condition condition = lock.newCondition();

    public void increment() throws Exception{
        lock.lock();
        try {
            while (number != 0) {
                //等待，不能生产
                condition.await();
            }

            //2、干活
            number++;
            System.out.println(Thread.currentThread().getName() + "\t " + number);

            //通知唤醒
            condition.signalAll();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }

    public void decrement() throws Exception{
        lock.lock();
        try {
            while (number == 0) {
                //等待，不能生产
                condition.await();
            }

            //2、干活
            number--;
            System.out.println(Thread.currentThread().getName() + "\t " + number);

            //通知唤醒
            condition.signalAll();
        }catch (Exception e){
            e.printStackTrace();
        }finally {
            lock.unlock();
        }
    }
}

/**
 * 题目：一个初始值为零的变量，两个线程对其进行交替操作，一个加1一个减1，来5轮
 * 1、线程     操作（方法）      资源类
 * 2、判断     干活              通知
 * 3、防止虚假唤醒
 */
public class ProdConsumer_TraditionDemo {


    public static void main(String[] args) {

        ShareData shareData = new ShareData();
        new Thread(()->{

            for (int i=0;i<5;i++){
                try {

                    shareData.increment();
                }catch (Exception E){
                    E.printStackTrace();
                }

            }

        },"AAA").start();


        new Thread(()->{

            for (int i=0;i<5;i++){
                try {

                    shareData.decrement();
                }catch (Exception E){
                    E.printStackTrace();
                }

            }

        },"BBB").start();


        new Thread(()->{

            for (int i=0;i<5;i++){
                try {

                    shareData.increment();
                }catch (Exception E){
                    E.printStackTrace();
                }

            }

        },"CCC").start();


        new Thread(()->{

            for (int i=0;i<5;i++){
                try {

                    shareData.decrement();
                }catch (Exception E){
                    E.printStackTrace();
                }

            }

        },"DDD").start();

    }

}
